Development of Ultrabright Semiconducting Polymer Dots for Ratiometric pH Sensing

Abstract

Semiconducting polymer-based nanoparticles (Pdots) have recently emerged as a new class of ultrabright probes for biological detection and imaging. This paper describes the development of poly(2,5-di(3', 7'-dimethyloctyl)phenylene-1,4-ethynylene) (PPE) Pdots as a platform for designing Förster resonance energy transfer (FRET)-based ratiometric pH nanoprobes. We describe and compare three routes for coupling the pH-sensitive dye, fluorescein, to PPE Pdots, which is a pH-insensitive semiconducting polymer. This approach offers a rapid and robust sensor for pH determination using the ratiometric methodology where excitation at a single wavelength results in two emission peaks, one that is pH-sensitive and the other one pH-insensitive for use as an internal reference. The linear range for pH sensing of the fluorescein-coupled Pdots is between pH 5.0 to 8.0, which is suitable for most cellular studies. The pH-sensitive Pdots show excellent reversibility and stability in pH measurements. In this paper, we use them to measure the intracellular pH in HeLa cells following their uptake by endocytosis, thus demonstrating their utility for use in cellular and imaging experiments.

Nanoparticles of Conjugated Molecules and Polymers for Biomedical Applications

“…Fluorescence imaging results using these NPs verified their targeting ability and internalization in HT29 cancer cells. [112]. Another example is intracellular temperature sensing achieved by applying NPs in which PFBT is incorporated into polystyrene labeled with Rhodamine B (RhB) [113].…”

Materials for FRET Analysis: Beyond Traditional Dye–Dye Combinations

“…These polymer dots, referred to as CPdots and later Pdots, are made from semiconducting polymer materials such as PPE, PFPV, or PFBT (see Figure 6.8 for full chemical name), are $4 nm in diameter with high fluorescent intensities, and could be readily functionalized [140][141][142]. Others have studied these Pdot materials, including Chan et al who developed FRET-based Pdots with photoswitching capabilities [143,144]. These were created through the incorporation of photochromic spiropyran molecules into a PFBT polymer and were intended for use in bioimaging applications.…”

Stark fluoreszierende halbleitende Polymerpunkte für Biologie und Medizin

“…[40][41][42][43][44] Es gab beachtliche Bemühungen, vielseitige halbleitende Polymernanopartikel (eine kleine Untergruppe davon sind die P-Punkte) zu erzeugen, ihre Eigenschaften und Funktionen einzustellen und deren Leistung für biomedizinische Untersuchungen zu verbessern. Die Forschungsbemühungen umfassen die Nutzung neuer Herstellungsverfahren, [45,46,69,70,72] die Untersuchung von NanopartikelBildungsmechanismen, [120,121] Sondierung der Photophysik der Nanopartikel, [47,49,54,122,123] Charakterisierung der Fluoreszenzleistung, [48,51,56,58] Abstimmung der Emissionsfarbe, [47,49,71,89] das Manipulieren der Partikeloberflä-che, [56-58, 64-66, 98, 102] die Verkapselung von anorganischen Materialien, [96,97,99,104,105] Entwicklung von Nanopartikelsensoren, [52,59,60,62,74,77] die Bildung von zellulären Strukturen, [56,57,[63][64][65][66] sowie das In-vivo-"Targeting" bei kleinen Tieren. [58,…”